This is copied from http://www.guidetojapanese.org/should.html of Tae Kim. Using はず to describe an expectation はず is used to express something that was or is supposed to be. You can treat はず just like a regular noun as it is usually attached to the adjective or verb that is supposed to be or supposed to happen.
The only thing to be careful about here is expressing an expectation of something not happening. To do this, you must use the negative existence verb ない to say that such an expectation does not exist. This might be in the form of 〜はずがない or 〜はずはない depending on which particle you want to use. The negative conjugation はずじゃない is really only used when you want to confirm in a positive sense such as 〜はずじゃないか？.
"S hazu" expresses the speakers expectation, not in the sense of hoping or looking forward to something, but in the sense that the proposition expressed by S should be true or come true. Thus, when the speaker uses <b>hazu</b>, he is not merely guessing, but stating a proposition based on reliable information or knowledge.
Bharat > thanks for the format, I added as a Note since it is a good example of conjugation.
I changed ex #5374 to fit the grammar entry according to the last 3 notes. I modified ex #5363 choosing 急須（きゅうす）as Mikiさん said below.
ex #5363 ぽっと shold be ポット. If the tea is Japanese tea, it should be 急須（きゅうす）.
bamboo4 I think 来たはずだ means that I believe he should have been here. If that is the fact that he was here, we would clearly say 彼はここに来ました。What do you think? dc #5374 文字化けしています。maybe 可能性はずっと低くなる ?? Also, I think 英語を話せなければ would be more natural.
umm, 文字化け yes or no, #5374 is は(wa) and ずっと, not はず and っと. It should be deleted.
来るはずだっだ or 来たはずだ? The examples use the former format while the notes illustrate the latter - are both correct? If so, is one more natural or is there a rule involved with choosing which to use?
来るはずだっだ means he was supposed to be here, while 来たはずだ means it is certain that he was here.
I agree with mankind.
Is this correct? This house must be Mr Tanaka's この家は田中さんのはずです。
so はず can have the meaning of "certain" rather than "probable" when it is used about a past event? I added the last three examples to hilite this...
はず means the slip provided at the end of an arrow to provide a fit with the bow string, which turned into the meaning of "naturally, of course, logically correct, etc." そんな筈はない therefore means that "there is no such fitting" i.e., it cannot be or logically not possible.
はず is used in a number of ways, XXはずがない literally "There's no expection of XX" used for "There's no way XX" "There's no chance of XX"